Function xStreamBufferReceive

stream_buffer.c:752–853

/*-----------------------------------------------------------*/

size_t xStreamBufferReceive( StreamBufferHandle_t xStreamBuffer,
                             void * pvRxData,
                             size_t xBufferLengthBytes,
                             TickType_t xTicksToWait )
{
    StreamBuffer_t * const pxStreamBuffer = xStreamBuffer;
    size_t xReceivedLength = 0, xBytesAvailable, xBytesToStoreMessageLength;

    configASSERT( pvRxData );
    configASSERT( pxStreamBuffer );

    /* This receive function is used by both message buffers, which store
     * discrete messages, and stream buffers, which store a continuous stream of
     * bytes.  Discrete messages include an additional
     * sbBYTES_TO_STORE_MESSAGE_LENGTH bytes that hold the length of the
     * message. */
    if( ( pxStreamBuffer->ucFlags & sbFLAGS_IS_MESSAGE_BUFFER ) != ( uint8_t ) 0 )
    {
        xBytesToStoreMessageLength = sbBYTES_TO_STORE_MESSAGE_LENGTH;
    }
    else
    {
        xBytesToStoreMessageLength = 0;
    }

    if( xTicksToWait != ( TickType_t ) 0 )
    {
        /* Checking if there is data and clearing the notification state must be
         * performed atomically. */
        taskENTER_CRITICAL();
        {
            xBytesAvailable = prvBytesInBuffer( pxStreamBuffer );

            /* If this function was invoked by a message buffer read then
             * xBytesToStoreMessageLength holds the number of bytes used to hold
             * the length of the next discrete message.  If this function was
             * invoked by a stream buffer read then xBytesToStoreMessageLength will
             * be 0. */
            if( xBytesAvailable <= xBytesToStoreMessageLength )
            {
                /* Clear notification state as going to wait for data. */
                ( void ) xTaskNotifyStateClear( NULL );

                /* Should only be one reader. */
                configASSERT( pxStreamBuffer->xTaskWaitingToReceive == NULL );
                pxStreamBuffer->xTaskWaitingToReceive = xTaskGetCurrentTaskHandle();
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        taskEXIT_CRITICAL();

        if( xBytesAvailable <= xBytesToStoreMessageLength )
        {
            /* Wait for data to be available. */
            traceBLOCKING_ON_STREAM_BUFFER_RECEIVE( xStreamBuffer );